Low profile ionization detector

ABSTRACT

Embodiments relate generally to systems and methods for a low profile PID typically including a flexible substrate; two or more electrodes containing an array of holes; a spacer with one or more holes; and two or more contacts corresponding to the electrodes. Typically, the unfolded flexible substrate defines a plane, and the electrodes are disposed on the flexible substrate such that when the flexible substrate is folded, one electrode is located on a top plane and another electrode is located on a bottom plane and the spacer is disposed between the electrodes to form an ionization chamber for use with a UV radiation source.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not applicable.

BACKGROUND

A photoionization detector (PID) can be used to detect the presence andconcentration of toxic gases, such as volatile organic compounds (VOCs),present in the surrounding atmosphere which can pose a threat to humans.The PID can measure VOCs in low concentrations from parts per million(ppm) down to the parts per billion (ppb). A PID is a very sensitivebroad-spectrum monitor.

For example, a PID might be used in a PID employs an ultraviolet (UV)lamp to emit photons that ionize target gases in the proximity ofdetector electrodes. An electric field is established between the platesof the electrodes by an applied voltage bias. The electric field inducesionized particles to move to one or another plate, thereby establishingan electric current between the electrodes. The electric current can beprocessed to provide an indication of the presence of one or moreionizable gases. The gases break down into positive and negative ionsthat are measured with an ionization detector. Ionization occurs when amolecule absorbs the high-energy UV light, which excites the moleculeand results in the temporary loss of a negatively charged electron andthe formation of positively charged ion. The gas becomes electricallycharged. In the PID, the charged particles produce a current that isamplified and converted to (or related to) a concentration measurement,and displayed on the meter as “ppm” or “ppb” or another concentrationmeasurement. The ions recombine after passing the electrodes in theionization detector to re-form the original molecule. PIDs arenon-destructive; they do not “burn” or permanently alter the sample gas,which allows them to be used for sample gathering. The ionizationdetector (e.g. PID) plays an important role in the performance of thePID sensor, affecting accuracy and linearity.

SUMMARY

In an embodiment, a low profile PID sensor may comprise an ultravioletradiation source; a flexible substrate; two or more electrodescontaining an array of holes (which typically pass through the flexiblesubstrate as well); a spacer with one or more holes; and one or morecontacts; wherein the (unfolded) flexible substrate defines a plane, andwherein the electrodes are disposed on the surface of the flexiblesubstrate such that when the flexible substrate is folded, one electrodeis located on a top (or first) plane and another electrode is located ona (separate, different) bottom (or second) plane and the spacer isdisposed between the electrodes.

In an embodiment, a method of manufacturing a low profile PID maycomprise printing (e.g. a pattern of electrode material to form) two ormore electrodes and corresponding contacts onto a (flat, planar)flexible substrate (when the flexible substrate is in the unfoldedconfiguration), wherein the pattern of the electrodes may contain anarray of holes; folding the flexible substrate such that when theflexible substrate is folded one electrode is located on a top (orfirst) plane and another electrode is located on a (separate, different)bottom (or second) plane; inserting a spacer in the plane parallelbetween the top plane and bottom plane of the folded flexible substrate;bonding the spacer to the folded flexible substrate; and assembling thefolded flexible substrate into a sensor module containing an ultravioletradiation source.

In an embodiment, a low profile photoionization detector assembly foruse with a low profile photoionization detector may comprise a biaselectrode; a sensing electrode; a guard electrode; one or more contacts;a spacer; and a flexible substrate; wherein the guard electrode isconfigured to surround the sensing electrode, and wherein the biaselectrode, sensing electrode, guard electrode, and the one or more(corresponding) contacts are printed onto the (flat, planar) flexiblesubstrate (when in unfolded configuration and wherein the flexiblesubstrate is configured to be folded such that when folded, the sensingelectrode and guard electrode are disposed on one (e.g. a first) planeand the bias electrode is disposed on a separate/different plane (e.g. asecond plane).

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure, referenceis now made to the following brief description, taken in connection withthe accompanying drawings and detailed description, wherein likereference numerals represent like parts.

FIG. 1A illustrates a perspective view of an unfolded PID according toan embodiment.

FIG. 1B illustrates a perspective view of an unfolded PID according toan embodiment.

FIG. 2 illustrates a perspective view of an unfolded PID according to anembodiment.

FIG. 3A illustrates a perspective view of a folded PID according to anembodiment.

FIG. 3B illustrates a perspective view of a folded PID according to anembodiment.

FIG. 4A illustrates a cross sectional view of a folded PID according toan embodiment.

FIG. 4B illustrates a cross sectional view of a folded PID according toan embodiment.

FIG. 5A illustrates a perspective view of a PID according to anembodiment.

FIG. 5B illustrates a perspective view of a PID according to anembodiment.

FIG. 6 illustrates a method of manufacturing a PID according to anembodiment.

DETAILED DESCRIPTION

It should be understood at the outset that although illustrativeimplementations of one or more embodiments are illustrated below, thedisclosed systems and methods may be implemented using any number oftechniques, whether currently known or not yet n existence. Thedisclosure should in no way be limited to the illustrativeimplementations, drawings, and techniques illustrated below, but may bemodified within the scope of the appended claims along with their fullscope of equivalents.

The following brief definition of terms shall apply throughout theapplication:

The term “comprising” means including but not limited to, and should beinterpreted in the manner it is typically used in the patent context;

The phrases “in one embodiment,” “according to one embodiment,” and thelike generally mean that the particular feature, structure, orcharacteristic following the phrase may be included in at least oneembodiment of the present invention, and may be included in more thanone embodiment of the present invention (importantly, such phrases donot necessarily refer to the same embodiment);

If the specification describes something as “exemplary” or an “example,”it should be understood that refers to a non-exclusive example;

The terms “about” or “approximately” or the like, when used with anumber, may mean that specific number, or alternatively, a range inproximity to the specific number, as understood by persons of skill inthe art field; and

If the specification states a component or feature “may,” “can,”“could,” “should,” “would,” “preferably,” “possibly,” “typically,”“optionally,” “for example,” “often,” or “might” (or other suchlanguage) be included or have a characteristic, that particularcomponent or feature is not required to be included or to have thecharacteristic. Such component or feature may be optionally included insome embodiments, or it may be excluded.

Embodiments of the disclosure include ionization detectors (e.g. PIDs),PID sensors and/or assemblies, and systems and methods of manufacturinga PID) and/or PID sensor/assembly using a flexible substrate comprisingelectrodes and contacts located on (for example, printed on) theflexible substrate (where the flexible substrate may be similar toflexible printed circuits (“FPC”)). Disclosed ionization detectors (e.g.PID) may include a flexible substrate, (which initially may beflat/planar during construction of the PID but later is) folded to spana first or top plane and a second or bottom plane (which is differentfrom and typically may be parallel to the first/top plane); two or moreelectrodes (and typically also their corresponding contacts)(e.g. alllocated on the flexible substrate (e.g. printed on the flexiblesubstrate); and a spacer (typically insulating); wherein a first of thetwo or more electrodes may be located on a first/top plane, a second ofthe two or more electrodes may be located on a second/bottom plane (e.g.parallel to the first plane), and a spacer is disposed/located betweenthe first and second electrodes; wherein the spacer comprises one ormore holes/apertures; and wherein each of the first and secondelectrodes comprises one or more and typically a plurality ofholes/apertures in an array) which pass through the flexible substrate(as well as the electrode material). Typically, the electrodes may beprinted onto one or more surface of the flexible substrate when theflexible substrate at least the portion of the flexible substrate withthe electrodes) is not folded but is ion a flat, planar, or unfoldedstate. After printing (or otherwise forming or attaching) the electrodesonto the flexible substrate, the flexible substrate would be folded sothat a first electrode would be located in a top/first plane and thesecond electrode would be located in a bottom/second plane, with thespacer located therebetween. This configuration forms an ionizationchamber between the electrodes, typically having a thickness based onthe spacer. Typically, the first electrode would be a bias electrode,and the second electrode would be a sensing electrode. In someembodiments, the PID might further include a third electrode. Forexample, the third electrode might be a guard electrode located on thesame plane with the second/sensing electrode, typically with the guardelectrode (at least partially) surrounding the sensing electrode. Forexample, the guard electrode might comprise a ring surrounding the biaselectrode. Thus, the guard electrode for disclosed embodiments typicallywould not be located on a different plane from the sensing electrodeand/or would not be located between the sensing and bias electrodes.Typically, the bias electrode and the sensing electrode would includeone or more (and typically a plurality or array of) holes/apertures(which typically also pass through the underlying flexible substrate onwhich the electrode is formed), while the guard may not include anyholes/apertures (e.g. through the flexible substrate). Some embodimentsmight include PID sensors/assemblies with a disclosed PID. Such PIDsensors/assemblies might further comprise (in addition to the PID withfolded substrate) a UV radiation source (which for example might bedirected to project UV light into the ionization chamber, for examplethrough the holes/apertures in the bias electrode). So a typicaldisclosed PID configuration might have the bias electrode locatedproximal to the UV radiation source and the sensing electrode locateddistal to the UV radiation source, with the bias electrode configured sothat the UV light enters the ionization chamber through the holes andthe gas sample may enter the ionization chamber through theholes/apertures in the sensing electrode. Such embodiments with aflexible substrate may allow for a smaller assembly that includes theelectrodes and contacts when compared to typical PIDs. Additionally, byreducing the number of components in the PID, the PID can be made muchsmaller compared to existing PIDs, the assembly and manufacturingprocess can be simplified and the cost of the PID can be lowered.

Embodiments of the disclosure include a method of manufacturing a PIDthat may comprise forming an FPC with two or more electrodes (andtypically also with their corresponding contacts/contactors) (e.g. withthe electrodes located on a flexible substrate), folding the initiallyplanar FPC so that the first electrode is located in a different(typically substantially parallel) plane from the second electrode,inserting a spacer between the folded FPC (e.g. between the two planeswith different electrodes), and/or boding the spacer to the (folded)FPC. Forming an FPC may comprise forming (which might include attachingor printing) electrodes onto a flexible substrate. Forming the FPC mightinclude forming a sensing electrode and a bias electrode on a flexiblesubstrate, surrounding a sensing electrode with a guard electrode on thesame plane and placing the biasing electrode on a separate plane (e.g.by folding the flexible substrate). This layout may prevent positiveions from being trapped on the guard electrode which can cause errors inmeasurement. Embodiments of the disclosure may also comprise a systemwhere the sensing electrode and bias electrode may be placed closertogether (than in a typical PID), thereby minimizing the interference ofhumidity and condensation in the measurement, which can cause falsealarms, decay of the electrodes, and a spike in the current.

Turning now to FIG. 1A-3, an exemplary low profile PID 100 is shown.FIGS. 1A-1B show the PID 100 in unfolded configuration (without spacer,while FIG. 2 further shows the spacer) In FIG. 1A, the low profile PID100 may comprise a flexible substrate 102 that makes up the basematerial and acts as insulation and/or support for one or more otherelements of the PID 100. In some embodiments, the flexible substrate 102may comprise a flexible material such as a fluorinated polymer (e.g.,PTFE, etc.), sold commercially as TEFLON™. Other insulating, heatresistant and low gas adsorbing flexible substrates 102 may be used, forexample, fluorinated ethylene propylene (FEY), perfluoroalkoxy alkane(PFA), polyimide, polyester, and/or a combination thereof. FIG. 1A showsa first side 122 of the PID 100 in unfolded configuration that, oncefolded, would typically become the inside of the low profile PID 100.The thickness of flexible substrate 102 can range anywhere betweenapproximately 0.1 millimeters (mm) to approximately 0.2 mm. In anembodiment, multiple layers of flexible substrate 102 can be used (forexample, instead of folding a single layer, two separate layers offlexible substrate (each with at least one electrode) could be used.

In some embodiments, the low profile PID 100 may comprise two or moreelectrodes, such as a sensing electrode 104, a bias electrode 106, and aguard electrode 108. The PID 100, with electrodes formed on or attachedto the flexible substrate, may comprise a flexible printed circuit board(“FPC”). Generally, a flexible printed circuit board is a bendable boardbased on a thin insulating film on which a circuit pattern (e.g.electrodes and/or contacts) is formed. Typically, a flexible printedcircuit board may be manufactured by etching a copper foil laminated ona flexible insulation material, and/or by printing conductive paste orink into a circuit pattern on an insulation material (e.g. a flexiblesubstrate) and then plating the circuit pattern. In one embodiment, theone or more electrodes 104, 106, and 108 are made by printing theelectrode circuit pattern onto the flexible substrate 102 using coppercoated with gold. Other conductive materials may be used in place ofcopper, such as gold, hastelloy, and the like. The gold coating is inertto ozone which reduces decay of the electrode. In another embodiment,the one or more electrodes 104, 106, and 108 are made by printing theelectrode circuit pattern onto the flexible substrate 102 on both thefirst side 122 of the flexible substrate 102 and a second side 124 ofthe flexible substrate 102 (shown in FIG. 1B). Typically, the sensingand bias electrodes might be similar in size and/or positioned when theflexible substrate is in folded configuration so that they substantiallyoverlap.

In an embodiment, the sensing electrode 104 may be printed onto theflexible substrate 102 in a pattern that contains one or more (e.g. anarray of) holes 118 that extend through the flexible substrate 102 fromthe first side 122 to the second side 124. In an embodiment, the biaselectrode 106 may be printed on the flexible substrate 102 in a patternthat contains one or more (e.g. an array of) holes 120 that extendthrough the flexible substrate 102 from the first side 122 to the secondside 124. In other words, the holes in the sensing and bias electrodes(104, 106) typically pass through the underlying flexible substrate 102(e.g. the holes may be pre-formed in the flexible substrate, such thatformation of the electrodes may occur with matching holes through theelectrode and the substrate). In embodiments having one or moreelectrode formed on both the first and second sides of the flexiblesubstrate 102 (when unfolded), typically such electrode would include ametallized layer on both the first and second sides of the flexiblesubstrate, with the metallized patterns/layers on the first and secondsides in conduction through metallized holes (e.g. the electrodematerial forming the metallized layers may also span the sidewalls ofthe holes in the electrode and/or substrate to electrically connect thefirst and second sides of the same electrode into an electricallyunitary whole). In some embodiments, one or more of the electrodes mightbe formed/located on only one side/surface of the flexible substrate102. In the embodiment shown in FIGS. 1A-1B, the diameter of the holes118 in the sensing electrode 104 is larger than the diameter of theholes 120 in the bias electrode 106. In some embodiments, the locationsof the holes in the sensing electrode may match/align with the holes inthe bias electrode when the flexible substrate is in its foldedconfiguration. The combined open surface area of all holes in the biaselectrode 106 may depend on the hole diameter and the minimum distancebetween the holes. In some embodiments, the diameter of the holes 120 inthe bias electrode is 0.5 mm and the distance between the holes 120 isapproximately 0.5 mm or larger. The combined open surface area of allholes in the sensing electrode 104 may depend on the hole diameter andthe minimum distance between the holes. In some embodiments, thediameter of the holes 118 is 0.8 mm and the distance between the holes118 is approximately 0.2 mm or larger.

In an embodiment, the guard electrode 108 may be placed/located aroundand/or encircling the sensing electrode 104 to collect the leakagecurrent from the bias electrode 106 and to prevent interference in theelectric field distribution between the sensing electrode 104 and thebias electrode 106. Further, the potential of the guard electrode 108may be set and maintained at or near the potential of the sensingelectrode 104. Accordingly, the guard electrode 108 can trap chargemovement (that may be associated with condensation) from the biaselectrode 106 to the sensing electrode 104. Trapping the charge movementassociated with condensation may prevent false alarms and improvesaccuracy of measurements at conditions of high humidity.

FIG. 1A also shows an embodiment of the PID 100 comprising one or morecontacts 110, 112, and 113 (shown in FIG. 1B). Contact 110 may beassociated with the sensing electrode 104, contact 112 may be associatedwith the bias electrode 106, and contact 113 may be associated with theguard electrode 108. The contacts 110, 112, and 113 may be configured tocommunicate electric signals to/from the electrodes 104, 106, and 108.In some embodiments, the flexible substrate 102 may contain slots 114and 116 to assist with the folding of the low profile PID 100.

FIG. 1B shows an embodiment of a low profile PID 100 showing the secondside 124 of the PID. Once the low profile PID 100 is folded, the secondside 124 would typically become the outside of the low profile PID 100(e.g. with one electrode located on a first/top plane and anotherelectrode located on a second/bottom plane).

FIG. 2 illustrates an embodiment of the low profile PID 100 (in unfoldedconfiguration, e.g. during manufacture/construction) further comprisinga spacer 202. The spacer 202 may be placed atop a portion of theflexible substrate having either the sensing electrode 104 or biaselectrode 106, so that when the flexible substrate is folded, the spacerwould be located in a plane between (and typically substantiallyparallel to) the sensing and bias electrodes (which typically also wouldbe substantially parallel to each other). The spacer 202 may comprise aninsulating material such as a fluorinated polymer (e.g., PTFE, etc.),sold commercially as TEFLON™, fluorinated ethylene propylene (FEP),perfluoroalkoxy alkane (PEA), polyimide, polyester, or the like. Themaximum thickness or height of the spacer 202 may be approximately 2 mm.The minimum thickness or height of the spacer 202 may be approximately0.2 mm. Thus, for example, the spacer may have a thickness of 0.2-0.5mm, 0.2-0.7 mm, 0.2-1 mm, 0.2-1.2 mm, 0.2-1.5 mm, 0.2-1.7 mm, 0.2-7 mm,0.5-1 mm, 0.5-1.5 mm, 0.5-2 mm. 1-1.2 mm, or 1-1.5 mm. The spacer 202may contain one or more holes 204 to allow gas flow through the spacer202 (i.e., between the electrodes 104 and 106) to form the ionizationchamber between the electrodes in folded configuration. In theembodiment of FIG. 2, the spacer comprises only one hole 204, and thediameter of the hole 204 in the spacer 202 may be slightly larger thanthe inside diameter of the guard electrode 108. When assembled, thespacer 202, the sensing electrode 104, the bias electrode 106, and theguard electrode 108 form an ionization chamber of the low profile PID100, which is described in more detail below.

FIG. 3A illustrates the low profile PID 100 described above, where theflexible substrate 102 has been folded, forming folded low profile PID300 (e.g. ready for use in a sensor/assembly). The second side 124 isshown with the bias electrode 106 on the top. Contacts 110 and 112 arealso seen facing upward. FIG. 3B shows the reverse of the folded lowprofile PID 300 of FIG. 3A according to an embodiment of the disclosure.Second side 124 is shown now with the sensing electrode 104 and guardelectrode 108 on top (e.g. the reverse of the folded PID shown in FIG.3A). In FIGS. 3A-B, the spacer is sandwiched between the folded flexiblesubstrate top and bottom planes.

Turning to FIGS. 4A-4B, cross-sectional views of a folded low profilePID 300 are shown, where the folded low profile PID 300 is connected toan ultraviolet radiation source, shown as UV lamp 402, to form a PIDsensor/assembly 400. UV lamp 402 is configured to act as a light sourceand generate light and/or radiation. In other embodiments, the PIDsensor 400 may comprise another or different light source. Whiledescribed as light, the radiation may or may not be in the visiblespectrum. In general, the radiation can be selected to ionize one ormore gasses of interest (e.g., target gas(es)) where the wavelength orwavelength range of the radiation may be suitable for ionizing thetarget gas(es). The UV lamp 402 may function as a UV light source forthe PID sensor 400. In some embodiments, the UV lamp 402 may producevacuum ultraviolet (VUV) radiation. In some embodiments, the UV lamp 402may comprise one or more noble gasses sealed inside the UV lamp 402.Typically, the folded PID 300 is oriented/configured in the sensor 400so that the bias electrode 106 is proximal to the UV lamp 402, while thesensing electrode 104 and guard electrode 108 are distal to the UV lamp,and the UV lamp 402 would be configured/oriented to project UV lightinto the ionization chamber through the holes in the bias electrode 106.Typically, the sensing electrode 104 of the folded PID 300 would beoriented/configured in the sensor 400 so that a gas sample (e.g. the gassample to be tested/detected by the PID sensor) enter the ionizationchamber through the holes 118 in the sensing electrode 104.

As shown in FIG. 4B, in operation gas enters the low profile PID 300through the holes 118 of the sensing electrode 104, which is located onthe top plane of the low profile PID 300 when folded. The gas entersthrough the holes 118 and into the space between the top planecontaining the sensing electrode 104 and the bottom plane containing thebias electrode 106 of the folded low profile PID 300, which is enclosedby the spacer 202 to form the ionization chamber 404.

In some embodiments, the distance between the sensing electrode 104 andbias electrode 106 when folded (Which may also represent the height ofthe ionization chamber and the height of the spacer 202) may range froma maximum height of approximately 2 mm to a minimum height ofapproximately 0.2 mm. In alternative embodiments, the distance betweenthe sensing electrode 104 and bias electrode 106 when folded maycomprise any height between approximately 0.2 mm to 2 mm.

Turning to FIG. 5A, a low profile PID system 500 is shown according toan embodiment. The folded low profile PID 300 is shown prior to beingassembled with a PID sensor module 504 (which may contain electricalconnectors/pins/contacts and/or a UV lamp 402). FIG. 5B shows, accordingto an embodiment, the assembled low profile PID system 500. The foldedlow profile PID 300 may be placed into the PID sensor module 504 in theorientation shown in FIGS. 5A and 5B. Contact 112 (shown in FIG. 3A)associated with bias electrode 106 may be connected to a high voltage DCoutput pin 508 on the PID sensor module 504. Contact 110 (shown in FIG.3A) associated with the sensing electrode 104 may be connected to anamplifier input pin 506 on the PID sensor module 504. The potential ofthe guard electrode 108 may be set near to or the same as the potentialof the sensing electrode 104 (via the contact 113 of the guard electrode108).

In an embodiment, the PID sensor module 504 may also contain a ITV lamp402. A high voltage may be applied (from AC 500V 100 k Hz to AC 2500V100 k Hz) to the UV lamp 402 and UV light generated inside the lamp 402passes through the crystal window 406 (see FIG. 4B) and through theholes 120 of the bias electrode into the ionization chamber 404. Duringuse, gas inside the ionization chamber 404 may absorb the energy of theUV light and be ionized into charged ions. The charged ions move withinthe electric field between the bias electrode 106 and the sensingelectrode 104 and a signal may be detected as a current and/or potentialdifference between the electrodes 104 and 106. The sensing electrode 104collects the electrical signal which is amplified by the PID sensormodule 500 and transmitted to a display portion of the PID sensor module500 for reading the gas concentration. The working temperature range ofthe PID sensor module 500 may be between −20° C. to 65° C.

In FIG. 6, an exemplary method of manufacturing a low profile PID 600 isdescribed. At block 602, two or more electrodes 104 and 106 andrelated/corresponding contacts 110 and 112 may be printed on (orotherwise formed on or attached to) the flexible substrate 102 (e.g.forming a flexible printed circuit with electrodes on a flexiblesubstrate). In some embodiments, three electrodes might beprinted/formed/attached on the flexible substrate 102, with a sensingelectrode 104, a guard electrode 108, and a bias electrode 106, and withthe guard electrode 108 located around (e.g. encircling or surrounding)the sensing electrode 104. The pattern of the electrodes 104 and 106 inFIG. 6 are printed to contain an array of holes 118 and 120 (whichtypically pass through the underlying flexible substrate as well, forexample for the sensing and bias electrodes). In some embodiments havinga guard electrode, the guard electrode 108 might not have any suchholes). So for example, printing might result in an unfolded PID similarto FIGS. 1A-1B. At block 604, the flexible substrate 102 would be folded(e.g. in half) such that when the flexible substrate 102 is folded, oneelectrode (e.g. sensing electrode 104) is located on a top plane andanother electrode (e.g. bias electrode 106) is located on a bottom plane(and in some embodiments, the third electrode—guard electrode 108—mightalso be located on the top plane (for example in the same plane as thesensing electrode) e.g. forming a folded PID 300 similar to FIGS. 3A-B).At block 606, a spacer 202 may be inserted between the top and bottomplanes of the folded flexible substrate 102 (which might result in anunfolded PID similar to FIG. 2, or a folded PID similar to FIGS. 3A-B(with spacer sandwiched between the folded flexible substrate top andbottom planes)). At block 608, the spacer 202 may be bonded to theflexible substrate, e.g. with a heat resistant adhesive. Finally atblock 610, the folded low profile PID 300 may be inserted (e.g.assembled) into a PID sensor module 504 containing an ultravioletradiation source 402 (e.g. with the bias electrode oriented proximal tothe UV lamp and the sensing electrode oriented distal the UV lamp,similar to FIGS. 4A-5B). This could further include orienting the foldedPID 300 with respect to the radiation source (e.g. UV lamp 402) and/orthe gas sample, and/or directing the radiation source (e.g. UV lamp 402)towards the holes in the bias electrode of the folded PID 300.Additionally, the PID 300 could be electrically connected in the sensormodule via the contacts, for example with the contact of the biaselectrode connecting to a high voltage DC output pin on the sensormodule and the contact of the sensing electrode connecting to theamplifier input pin on the sensor module.

Having described various devices and methods herein, exemplaryembodiments or aspects can include, but are not limited to:

In a first embodiment, a low profile PID may comprise an ultravioletradiation source; a flexible substrate; two or more electrodescontaining an array of holes; a spacer with one or more holes; and oneor more contacts; wherein the flexible substrate defines a plane, andwherein the electrodes are disposed on the surface of the flexiblesubstrate such that when the flexible substrate is folded, one electrodeis located on a top plane and another electrode is located on a bottomplane and the spacer is disposed between the electrodes.

A second embodiment can include the low profile PID of the firstembodiment, wherein multiple layers of flexible substrate are used, eachwith at least one electrode.

A third embodiment can include the low profile PID of the first orsecond embodiment, wherein the flexible substrate contains a sensingelectrode, a bias electrode, and a guard electrode.

A fourth embodiment can include the low profile PID of any of the firstto third embodiments, wherein the PID with electrodes formed on orattached to the flexible substrate may comprise a flexible printedcircuit board.

A fifth embodiment can include the low profile PID of any of the firstto fourth embodiments, wherein the electrodes are made by printing theelectrode circuit pattern onto the flexible substrate using coppercoated with gold.

A sixth embodiment can include the low profile PID of any of the firstto fifth embodiments, wherein the electrodes are made by printing theelectrode circuit pattern onto the flexible substrate on both the firstside of the flexible substrate and the second side of the flexiblesubstrate.

A seventh embodiment can include the low profile PID of any of the firstto sixth embodiments, wherein the guard electrode surrounds the sensingelectrode and is configured to collect leakage current from the biaselectrode.

An eighth embodiment can include the low profile PID of any of the firstto seventh embodiments, wherein the sensing electrode, the biaselectrode, and the guard electrode are disposed on the flexiblesubstrate such that, when the flexible substrate is folded, the sensingelectrode and the guard electrode are located on the top plane and thebias electrode is located on the bottom plane, and wherein the biaselectrode is proximal to the ultraviolet radiation source, the sensingelectrode is distal to the ultraviolet radiation source, and theultraviolet radiation source is configured to direct light towards theholes in the bias electrode.

A ninth embodiment can include the low profile PID of any of the firstto eighth embodiments, wherein when the flexible substrate is folded,the distance between the sensing electrode and the bias electrode isless than 2 mm.

A tenth embodiment can include the low profile PID of any of the firstto ninth embodiments, wherein the bias electrode may be printed on theflexible substrate in a pattern that contains one or more holes thatextend through the flexible substrate from the first to the second side.

An eleventh embodiment can include the low profile PID of any of thefirst to tenth embodiments, wherein the sensing electrode may be printedon the flexible substrate in a pattern that contains one or more holesthat extend through the flexible substrate from the first to the secondside.

A twelfth embodiment can include the low profile PID of any of the firstto eleventh embodiments, wherein the guard electrode may be printed onthe flexible substrate in a pattern that contains one or more holes thatextend through the flexible substrate from the first to the second side.

A thirteenth embodiment can include the low profile PID of any of thefirst to twelfth embodiments, wherein electrodes that are formed on boththe first and second sides of the flexible substrate include ametallized layer on both the first and second sides of the flexiblesubstrate and wherein the metallized layers span the sidewalls of theholes on the electrode and/or substrate to electrically connect/conductthe first and second sides of the same electrode into an electricallyunitary whole.

A fourteenth embodiment can include the low profile PID of any of thefirst to thirteenth embodiments, wherein the diameter of the holes ofthe sensing electrode are larger than the diameter of the holes of thebias electrode.

A fifteenth embodiment can include the low profile PID of any of thefirst to fourteenth embodiments, wherein the diameter of the hole in thespacer is larger than the inside diameter of the guard electrode.

A sixteenth embodiment can include the low profile PID of any of thefirst to fifteenth embodiments, wherein the location of the holes in thesensing electrode may match/align with the location of the holes in thebias electrode when the flexible substrate is in a folded configuration.

A seventeenth embodiment can include the low profile PID of any of thefirst to sixteenth embodiments, wherein the spacer, the sensingelectrode, the bias electrode, and the guard electrode form anionization chamber.

An eighteenth embodiment can include the low profile PID of any of thefirst to seventeenth embodiments, wherein the low profile PID in anunfolded configuration comprises a spacer and wherein the spacer may beplaced atop a portion of the flexible substrate having either thesensing electrode or bias electrode, so that when the flexible substrateis folded, the space would be located in a place between the sensing andbias electrodes.

A nineteenth embodiment can include the low profile PID of any of thefirst through eighteenth embodiments, wherein the flexible substratecomprises polytetrafluoroethylene (PTFE).

A twentieth embodiment can include the low profile PID of any of thefirst through nineteenth embodiments, wherein the spacer comprisespolytetrafluoroethylene (PTFE).

A twenty-first embodiment can include the low profile PID of any of thefirst through twentieth embodiments, wherein the spacer may have amaximum thickness of approximately 2 mm.

A twenty-second embodiment can include the low profile PID of any of thefirst through twenty-first embodiments, wherein the spacer may have aminimum thickness of approximately 0.2 mm.

A twenty-third embodiment can include the low profile PID of any of thefirst through twenty-second embodiments, wherein the electrodes andcontacts comprise a flexible printed circuit consisting of copper coatedwith gold.

A twenty-fourth embodiment can include the low profile PID of any of thefirst through twenty-third embodiments, wherein the contacts areconnected to a high voltage DC power source and amplifier.

A twenty-fifth embodiment can include the low profile PID of any of thefirst through twenty-fourth embodiments, wherein the folded PID isoriented in the sensor so that the bias electrode is proximal to the UVlamp, the sensing electrode and guard electrode are distal to the UVlamp, and the UV lamp is configured/oriented to project UV light eionization chamber through the holes in the bias electrode.

A twenty-sixth embodiment can include the low profile PID of any of thefirst through twenty-fifth embodiments, wherein the sensing electrode ofthe folded PID is configured/oriented in the sensor so that a gas samplemay enter the ionization chamber through the holes in the sensingelectrode.

In a twenty-seventh embodiment, a method for manufacturing a low profilePID sensor may comprise printing two or more electrodes and contactsonto a flexible substrate, wherein two of the electrodes include anarray of holes which pass through the flexible substrate; folding theflexible substrate such that, when the flexible substrate is folded, oneelectrode is located on a top plane and another electrode is located ona bottom plane; inserting a spacer in a parallel plane between the topplane and bottom plane of the folded flexible substrate; and bonding thespacer to the folded flexible substrate.

A twenty-eighth embodiment can include the method of the twenty-seventhembodiment, wherein three electrodes might be printed/formed/attached onthe flexible substrate, with a sensing electrode, a guard electrode, anda bias electrode, and wherein the guard electrode is located around orencircles the sensing electrode.

A twenty-ninth embodiment can include the method of either the twentyseventh or the twenty-eighth embodiment, wherein printing the two ormore electrodes comprises printing a bias electrode and correspondingcontact to the flexible substrate; printing a sensing electrode andcorresponding contact to the flexible substrate; printing a guardelectrode to the flexible substrate; and wherein folding the flexiblesubstrate comprises folding the flexible substrate such that when theflexible substrate is folded, the sensing electrode and the guardelectrode are located on the top plane and the bias electrode is locatedon the bottom plane.

A thirtieth embodiment can include the method of any one of thetwenty-seventh to twenty-ninth embodiments, wherein the pattern of thetwo or more electrodes are printed to contain an array of holes whichtypically pass through the underlying flexible substrate.

A thirty-first embodiment can include the method of any one of thetwenty-seventh to thirtieth embodiments, wherein the folded low profilePID 300 may be inserted (e.g. assembled) into a sensor module containingan ultraviolet radiation source with the bias electrode orientedproximal to the UV lamp and the sensing electrode oriented distal the UVlamp and wherein the radiation source and/or the gas sample is directedtowards the holes in the bias electrode of the folded PID.

A thirty-second embodiment can include can include the method of any oneof the twenty-seventh to thirty-first embodiments, further comprisingassembling the folded flexible substrate into a sensor module containingan ultraviolet radiation source; connecting the contact of the biaselectrode to a high voltage DC output pin on the sensor module andconnecting the contact of the sensing electrode to an amplifier inputpin on the sensor module.

A thirty-third embodiment can include can include the method of any oneof the twenty-seventh to thirty-second embodiments, wherein the sensingelectrode and bias electrode are printed such that the diameter of theholes of the sensing electrode are larger than the holes of the biaselectrode.

A thirty-fourth embodiment can include can include the method of any oneof the twenty-seventh to thirty-third embodiments, wherein the flexiblesubstrate is folded such that the distance between the top plane and thebottom plane is less than 2 mm.

In a thirty-fifth embodiment, a low profile PID assembly for use with alow profile PID, the low profile PID assembly comprising a biaselectrode; a sensing electrode; a guard electrode; one or more contacts;a spacer; and a flexible substrate, wherein the guard electrode isconfigured to surround the sensing electrode; the bias electrode, thesensing electrode, the guard electrode, and the one or more contacts areprinted onto the flexible substrate; and the flexible substrate isconfigured to be folded such that when folded, the sensing electrode andguard electrode are disposed on one plane and the bias electrode isdisposed on a separate plane.

A thirty-sixth embodiment can include the low profile PID assembly ofthe thirty-fifth embodiment, wherein when the flexible substrate isfolded, the distance between the sensing electrode and the biaselectrode of the flexible substrate is less than 2 mm.

A thirty-seventh embodiment can include the low profile PID assembly ofany one of the thirty-fifth or thirty-sixth embodiments, wherein thesensing electrode and the bias electrode are printed onto the flexiblesubstrate with an array of holes.

A thirty-eighth embodiment can include the low profile PID assembly ofany one of the thirty-fifth through thirty-seventh embodiments, whereinthe sensing electrode and the bias electrode are printed such that thediameter of the holes of the sensing electrode is larger than thediameter of the holes of the bias electrode.

A thirty-ninth embodiment can include the low profile PID assembly ofany one of the thirty-fifth through thirty-eighth embodiments, whereinthe flexible substrate comprises polytetrafluoroethylene (PTFE).

While various embodiments in accordance with the principles disclosedherein have been shown and described above, modifications thereof may bemade by one skilled in the art without departing from the spirit and theteachings of the disclosure. The embodiments described herein arerepresentative only and are not intended to be limiting. Manyvariations, combinations, and modifications are possible and are withinthe scope of the disclosure. Alternative embodiments that result fromcombining, integrating, and/or omitting features of the embodiment(s)are also within the scope of the disclosure. Accordingly, the scope ofprotection is not limited by the description set out above, but isdefined by the claims Which follow that scope including all equivalentsof the subject matter of the claims. Each and every claim isincorporated as further disclosure into the specification and the claimsare embodiment(s) of the present invention(s). Furthermore, anyadvantages and features described above may relate to specificembodiments, but shall not limit the application of such issued claimsto processes and structures accomplishing any or all of the aboveadvantages or having any or all of the above features.

Additionally, the section headings used herein are provided forconsistency with the suggestions under 37 C.F.R. 1.77 or to otherwiseprovide organizational cues. These headings shall not limit orcharacterize the invention(s) set out in any claims that may issue fromthis disclosure. Specifically and by way of example, although theheadings might refer to a “Field,” the claims should not be limited bythe language chosen under this heading to describe the so-called field.Further, a description of a technology in the “Background” is not to beconstrued as an admission that certain technology is prior art to anyinvention(s) in this disclosure. Neither is the “Summary” to beconsidered as a limiting characterization of the invention(s) set forthin issued claims. Furthermore, any reference in this disclosure to“invention” in the singular should not be used to argue that there isonly a single point of novelty in this disclosure. Multiple inventionsmay be set forth according to the limitations of the multiple claimsissuing from this disclosure, and such claims accordingly define theinvention(s), and their equivalents, that are protected thereby. In allinstances, the scope of the claims shall be considered on their ownmerits in light of this disclosure, but should not be constrained by theheadings set forth herein.

Use of broader terms such as “comprises,” “includes,” and “having”should be understood to provide support for narrower terms such as“consisting of,” “consisting essentially of,” and “comprisedsubstantially of” Use of the terms “optionally,” “may,” “might,”“possibly,” and the like with respect to any element of an embodimentmeans that the element is not required, or alternatively, the element isrequired, both alternatives being within the scope of the embodiment(s).Also, references to examples are merely provided for illustrativepurposes, and are not intended to be exclusive.

While several embodiments have been provided in the present disclosure,it should be understood that the disclosed systems and methods may beembodied in many other specific forms without departing from the spiritor scope of the present disclosure. The present examples are to beconsidered as illustrative and not restrictive, and the intention is notto be limited to the details given herein. For example, the variouselements or components may be combined or integrated in another systemor certain features may be omitted or not implemented.

Also, techniques, systems, subsystems, and methods described andillustrated in the various embodiments as discrete or separate may becombined or integrated with other systems, modules, techniques, ormethods without departing from the scope of the present disclosure,Other items shown or discussed as directly coupled or communicating witheach other may be indirectly coupled or communicating through someinterface, device, or intermediate component, whether electrically,mechanically, or otherwise. Other examples of changes, substitutions,and alterations are ascertainable by one skilled in the art and could bemade without departing from the spirit and scope disclosed herein.

What is claimed is:
 1. A low profile photoionization detectorcomprising: an ultraviolet radiation source; a flexible substrate,wherein the flexible substrate contains a sensing electrode, a biaselectrode, and a guard electrode, wherein the guard electrode surroundsthe sensing electrode and is configured to collect leakage current fromthe bias electrode, and wherein each of two or more of the electrodescontain an array of holes; a spacer with one or more holes; and one ormore contacts, each of the one or more contacts electrically connectedto a corresponding one of the sensing electrode, the bias electrode, orthe guard electrode, wherein the flexible substrate defines a plane, andwherein the electrodes are disposed on the flexible substrate such that,when the flexible substrate is folded, one electrode is located on a topplane and another electrode is located on a bottom plane and the spaceris disposed between the electrodes.
 2. The low profile photoionizationdetector of claim 1, wherein the sensing electrode, the bias electrode,and the guard electrode are disposed on the flexible substrate suchthat, when the flexible substrate is folded, the sensing electrode andthe guard electrode are located on the top plane and the bias electrodeis located on the bottom plane; and wherein the bias electrode isproximal to the ultraviolet radiation source, the sensing electrode isdistal to the ultraviolet radiation source, and the ultravioletradiation source is configured to direct light towards the array ofholes in the bias electrode.
 3. The low profile photoionization detectorof claim 1, wherein when the flexible substrate is folded, the distancebetween the sensing electrode and the bias electrode is less than 2 mm.4. The low profile photoionization detector of claim 1, whereindiameters of the holes of the sensing electrode are larger thandiameters of the holes of the bias electrode.
 5. The low profilephotoionization detector of claim 1, wherein a diameter of the one ormore holes in the spacer is larger than an inside diameter of the guardelectrode.
 6. The low profile photoionization detector of claim 1,wherein the flexible substrate comprises polytetrafluoroethylene.
 7. Thelow profile photoionization detector of claim 1, wherein the electrodesand the one or more contacts comprise a flexible printed circuitconsisting of copper coated with gold.
 8. The low profilephotoionization detector of claim 1, wherein the one or more contactsare connected to a high voltage DC power source and amplifier.
 9. Amethod of manufacturing a low profile photoionization detector sensor,the method comprising: printing a bias electrode and a correspondingcontact onto a flexible substrate; printing a sensing electrode andcorresponding contact onto the flexible substrate; printing a guardelectrode onto the flexible substrate, wherein the guard electrodesurrounds the sensing electrode and is configured to collect leakagecurrent from the bias electrode, wherein each of two of the printedelectrodes include an array of holes which pass through the flexiblesubstrate, and wherein each of the corresponding contacts iselectrically connected to the corresponding one of the sensing electrodeor the bias electrode; folding the flexible substrate such that, whenthe flexible substrate is folded, one electrode is located on a topplane and another electrode is located on a bottom plane; inserting aspacer in a parallel plane between the top plane and the bottom plane ofthe folded flexible substrate; and bonding the spacer to the foldedflexible substrate.
 10. The method of claim 9, wherein folding theflexible substrate comprises folding the flexible substrate such thatwhen the flexible substrate is folded, the sensing electrode and theguard electrode are located on the top plane and the bias electrode islocated on the bottom plane.
 11. The method of claim 10, furthercomprising: assembling the folded flexible substrate into a sensormodule containing an ultraviolet radiation source; connecting thecorresponding contact of the bias electrode to a high voltage DC outputpin on the sensor module; and connecting the corresponding contact ofthe sensing electrode to an amplifier input pin on the sensor module.12. The method of claim 10, wherein the sensing electrode and the biaselectrode are printed such that diameters of the holes of the sensingelectrode are larger than diameters of the holes of the bias electrode.13. The method of claim 9, wherein the flexible substrate is folded suchthat the distance between the top plane and the bottom plane is lessthan 2 mm.
 14. A low profile photoionization detector assembly for usewith a low profile photoionization detector, the low profilephotoionization detector assembly comprising: a bias electrode; asensing electrode; a guard electrode; one or more contacts, each of theone or more contacts electrically connected to a corresponding one ofthe sensing electrode, the bias electrode, or the guard electrode; aspacer; and a flexible substrate, wherein: the guard electrode surroundsthe sensing electrode and is configured to collect leakage current fromthe bias electrode; the bias electrode, the sensing electrode, the guardelectrode, and the one or more contacts are printed onto the flexiblesubstrate; and the flexible substrate is configured to be folded suchthat when folded, the sensing electrode and the guard electrode aredisposed on one plane and the bias electrode is disposed on a separateplane.
 15. The low profile photoionization detector assembly of claim14, wherein when the flexible substrate is folded, the distance betweenthe sensing electrode and the bias electrode of the flexible substrateis less than 2 mm.
 16. The low profile photoionization detector assemblyof claim 14, wherein each of the sensing electrode and the biaselectrode are printed onto the flexible substrate with an array ofholes.
 17. The low profile photoionization detector assembly of claim16, wherein the sensing electrode and the bias electrode are printedsuch that diameters of the holes of the sensing electrode are largerthan diameters of the holes of the bias electrode.
 18. The low profilephotoionization detector assembly of claim 14, wherein the flexiblesubstrate comprises polytetrafluoroethylene (PTFE).